The Black Soldier Fly, Hermetia Illucens (Diptera: Stratiomyidae)
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Scientific African 5 (2019) e00134 Contents lists available at ScienceDirect Scientific African journal homepage: www.elsevier.com/locate/sciaf The black soldier fly, Hermetia illucens (Diptera: Stratiomyidae): Trapping and culturing of wild colonies in Ghana ∗ E.A. Ewusie a,b, , P.K. Kwapong b, G. Ofosu-Budu c, C. Sandrock d, A.M. Akumah c, E.K. Nartey c, C. Tetegaga d, S.K. Agyakwah e a Biotechnology and Nuclear Agriculture Research Institute, Ghana Atomic Energy Commission, P. O. Box LG, 80, Legon, Accra, Ghana b Department of Conservation Biology and Entomology, School of Biological Sciences, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana c Department of Soil Science, University of Ghana, P. O. Box LG 245, Legon, Accra, Ghana d Department of Marine and Fishery Science, University of Ghana, Legon, Accra, Ghana e CSIR –Water Research Institute, Aquaculture Research and Development Centre, P. O. Box 139, Akosombo, Ghana a r t i c l e i n f o a b s t r a c t Article history: The larvae of the black soldier fly (BSF), Hermetia illucens L. (Diptera: Stratiomyidae), are Received 7 April 2019 promising candidates to be utilized in alternative organic waste management and for fish Revised 2 July 2019 and livestock feed production. The scalability of this technology in Ghana will depend on Accepted 20 August 2019 a steady source of large numbers of BSF larvae. The objectives of this study were to iden- tify the most attractive organic manure dumps or heaps in the study area for trapping Keywords: wild BSF egg clutches and assess the effect of local environmental conditions on the trap- Colony management ping and laboratory rearing of BSF. The study compared the number of egg clutch trapped Feedstock at different microhabitats including piggery, chicken and sheep waste dumps and on a Larvae compost heap. The piggery dump waste was the most suitable site for trapping BSF egg Microhabitat clutches. No egg clutch was deposited nearby poultry and sheep waste microhabitats. Re- Waste dump sults showed no differences in temperature between microhabitats during egg trapping but relative humidity differed between poultry, sheep and compost, however this did not have any effect on egg clutch trapping. No significant differences in temperature and hu- midity were observed during larval rearing. Significant differences in weight and length of larvae from both piggery and compost sites were observed on days 5 and 10 after egg hatch. A small scale laboratory colony rearing has been successfully established in Ghana. The design of the larval breeding system appears to be suitable for respective up-scaling that could provide sufficient larval quantities for composting organic waste and producing feed components for livestock and fish. © 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY license. ( http://creativecommons.org/licenses/by/4.0/ ) ∗ Corresponding author at: Biotechnology and Nuclear Agriculture Research Institute, Ghana Atomic Energy Commission, P. O. Box LG, 80, Legon, Accra. Ghana. E-mail address: [email protected] (E.A. Ewusie). https://doi.org/10.1016/j.sciaf.2019.e00134 2468-2276/© 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY license. ( http://creativecommons.org/licenses/by/4.0/ ) 2 E.A. Ewusie, P.K. Kwapong and G. Ofosu-Budu et al. / Scientific African 5 (2019) e00134 Introduction The black soldier fly (BSF), Hermetia illucens , is a valuable insect species whose larvae have enormous potentials for con- verting organic waste into compost, while the larval biomass generated could also be harvested for its protein and fatty acid content [1] . Large quantities of black soldier fly larvae have to be generated so that they can be used to inoculate the organic fraction of the municipal solid waste, to convert it to compost. Similarly, large quantities of the larvae must be generated to meet demands for its use as protein-source for animal feed formulation. In order to meet the increasing demands for the larvae, for use in bioconversion of organic waste and biomass generation at any point in time, it is important to have a black soldier fly colony readily available. Therefore, colonization and production methods must be developed. Although there has been much research focusing on the use of BSF larvae to manage swine, chicken and cattle manure [7] , as well as municipal organic waste [9] , few reports have dealt with its progeny initiation from the wild [7] . Again, depending on the insect species, specific environmental requirements, for instance regarding temperature, humidity, feeding substrate need to be considered. Leppla [11] , collected BSF eggs from the wild, and reared them to adults in 38 days at 29.3 °C, however, he was unable to establish a larval population over multiple generations. Sheppard et al. [17] , collected eggs in an open-sided caged layer house and successfully maintained them in the laboratory, but was difficult to maintain suitable temperature essential for eliciting mating in the large greenhouse. The rearing of H. illucens designed for organic waste management, and also for fish and animal feed production has not received adequate attention, in spite of its immense prospects and economic potential. Much have been reported on the mass rearing of the BSFL in the developed countries [12 , 17] , with varying degrees of success. Facilities and environmental conditions that prevail in the temperate countries differ considerably from that of the tropics. Moreover, in developing countries such as Ghana, suitable facilities for rearing insects do not exist as can be found and reported in the developed nations. Locally, easily adaptable method has to be designed for the mass rearing of this insect, taking into considerations the major environmental factors such as relative humidity, temperature, light and feed. Thus, the study hypothesized that there will be variation in wild H . illucens egg clutches trapped on organic manure dumps or heaps in the study area. The objectives of this study were to: 1) identify the most attractive organic manure dumps or heaps for trapping wild BSF egg clutches, and 2) assess putative differences in successfully establishing a laboratory colony of BSF from wild collections under local envi- ronmental conditions. Materials and methods Study location The study was conducted at the Biotechnology and Nuclear Agriculture Research Institute (BNARI) of the Ghana Atomic Energy Commission (GAEC), Accra, Ghana. BNARI is located about 20 km north of Accra (5 °40 36.6 N; 0 °11 52.5 W, and 76 m above sea level). Colony initiation Study of the most suitable microhabitat or waste where BSF egg clutches can be easily harvested in the study area Five egg-laying traps prepared according to Sheppard et al. [17] and consisting of five plies of cut corrugated cardboard that were held together with a rubber band. Traps were 8 cm long and were placed at equidistance (10 cm between and within rows) from each other and 2 cm above the microhabitat (piggery waste dumpsite, poultry waste dumpsite, sheep waste dumpsite and a compost heap) ( Figs. 1 and 2 ). These microhabitats were of the same age (about three weeks old) but the piggery and sheep waste microhabitats received daily addition of waste from the pig and sheep staples. Egg collection was conducted every two weeks for 13 months (October, 2015–October, 2016). Temperature and relative humidity at three different sections of each microhabitat were taken on the day and at the time of trap set and their means recorded. Traps were checked for egg clutches 24 h after deployment and removed 48 h thereafter. This is because BSF eggs begin to hatch 3.5 days at 30 °C [22] or 4.3 days at 24 °C [17] . Incubation of harvested egg clutches Egg clutches sired were immediately transferred to a clean, moist surface in order to prevent microbial contamination [15] . The number of egg clutches sired in the grooves of the cardboard traps were counted and their weight determined using an analytical balance. The traps with egg clutches harvested from different microhabitats were incubated separately under ambient conditions on 50 g of finely grounded moistened layer chicken meal placed in 250 mL incubation boxes ( Fig. 3 ) with ventilated lids in the laboratory. Larval feeding Five days after egg clutch incubation, 10 0 0 larvae from each microhabitat replicated three times were picked with the aid of disinfected forceps and transferred separately into 50 L plastic containers. These plastic containers had been cleaned with detergent and disinfested with 70% alcohol and dried under the sun for at least 6 h. The 50 L plastic containers had ventilated lids to promote aeration, reduce generation of excessive heat and also to prevent the escape of larvae ( Fig. 4 ). E.A. Ewusie, P.K. Kwapong and G. Ofosu-Budu et al. / Scientific African 5 (2019) e00134 3 Fig. 1. Trapping of BSF egg clutches at different microhabitats (a) compost heap; (b) poultry waste dump. Temperature and relative humidity were monitored at 10.00 > a.m. from three different locations of the larval cages using digital thermohydrographs. Larvae were fed every 3rd day till the fifth instar stage when feeding was stopped. The larvae were reared on layer meal moistened to 70% in the laboratory under 12:12 L: D photoperiod. Feed given was computed based on a formula adapted from Stamer (Personal Communications, 2015) as follows: Number of larv ae × 0 . 1 g F eed amount (g) = × 25 × 70% (1) MC Where MC = moisture content of diet, 0.1 = Amount of feed per larvae per day [7] , adjusted every 3rd day, 25 = Estimated larval feeding duration (days) [4 , 23] , 70% = Adjusted moisture content of diets.